STOCKS of wild salmon in the River Tweed have fallen to an all-time low because of record numbers of predatory birds, according to new research.
Salmon catches dropped from a high of 23,000 in 2010 to an all-time low of 5,510 last year, prompting a study of the likely causes.
The Tweed Salmon Tracking Report 2019 tagged 60 salmon smolts at Gala Water in Galashiels, Roxburghshire, which is a tributary of the Tweed.
Only 16 of the smolts, which had been fitted with acoustic transmitters, returned, and large numbers of goosanders, a migratory river duck, are thought to be responsible for the decline.
The study, by the Tweed Foundation, complements previous dietary analysis of goosanders and cormorants from the river and, although the sample was small, has provided insights into the disappearance of wild fish.
Transmitter locations identified goosanders as being responsible for smolt mortality, with otters also blamed for some losses.
The Tweed Foundation said: ‘If the losses concentrated in the Middle Tweed accurately reflect the Tweed smolt population, then the implication may be that the current licensed management for goosanders needs to be reviewed, with planned tracking work in 2020 and 2021 testing alternative strategies for improving smolt survival.’
Salmon farms have often been blamed by the wild salmon lobby for declining stocks but recently – and in light of dwindling populations on rivers (such as the Tweed) where there are no nearby farms – attention has begun to shift to other possible culprits.
The Tweed Foundation said it is now looking at funding options to expand its study for future years.